Complications associated with hemodialysis vascular access are among the most important causes of morbidity and expense in end stage renal disease (ESRD) hemodialysis patients in the United States today. The most frequent cause of graft failure is thrombosis usually due to venous stenosis. Based on results from nonrandomized studies using historical controls, the National Kidney Foundation - Dialysis Outcomes Quality Initiative (NKF-DOQI) have recommended a program of routine monitoring and prophylactic repair of graft stenosis prior to development of graft thrombosis. The DOQI guidelines are widely considered to be the standard of care for hemodialysis patients. A randomized, controlled study of this prophylactic approach has been conducted at our institution and demonstrates no increase in duration of graft life but, in fact, an increased risk of infection in those patients assigned to angiographic intervention. The proposed study addresses the generalizability of these findings using a large, national database, the United States Renal Data System (USRDS) to examine the association between hemodialysis access procedures (angiograms and angioplasties) and graft infections. We will perform a retrospective, case-control study to determine whether patients who develop a graft infection are more likely to have had a graft angioplasty than a control group without graft infection. The improvement of hemodialysis vascular outcomes is an area of intense interest in the nephrology community and the optimal procedures for monitoring and maintenance have yet to be rigorously tested. The results of the proposed study will have important clinical and economic implications.